The invention relates to automatic letter processing and particular to systems, for which an automatic address reading method is supplemented and improved by the use of video coding. Automatic address reading systems (OCR) are well known in the field of letter processing and are described, for example, in German Patent DE 195 31 392. Modern OCR letter sorting systems can achieve letter processing rates of 10 letters per second, meaning 36,000 letters per hour and more. However, the recognition reliability varies considerably, depending upon the lettering style and total quality of the address information affixed to the letter surface. In case of successful recognition, the respective letter can be provided with a machine-readable bar code. This bar code permits a further mechanical processing up to a desired, optional sorting order. In particular, the use of bar codes permits a sorting of letters of up the sorting level of the postal run; for which the letters are sorted according to the distribution sequence used by the delivery person.
Owing to the fact that the recognition rates for automatic reading systems vary considerably, it is necessary to support automatic necessary processes through various forms of manual intervention. The simplest intervention is that of rejection letters not readable in automatic reading systems and using a hand sorting process on them. However, the resulting expenses are uneconomically high, given the increase in operational expenses. Added to this is the fact that a mechanical sorting of such postal goods is not possible without problems at a later point in time, for example, two separate flows of goods are created, which must then be combined again manually at a letter and specific point in time.
In order to avoid these disadvantages resulting from the manual sorting of OCR rejected items, various methods have been developed for manually coding postal goods. These methods use operator intervention to affix bar codes to the items in a manner that is consistent with the requirement to carry out a mechanical sorting with the same machines that process OCR-read and bar-coded mail.
Another method for coding rejected postal items uses manual or a manually operated coding stations. At these manually-operator, wherein the operator encodes enough information from each of these items, as is necessary to clearly identify the destination. For this, the input address is converted by means of a directory to a sorting bar code which is then affixed to the item. The coded items are subsequently processed further by means of bar code sorter (BCS), which are identical to OCR-suitable BCS. Manually operated coding stations of this type were first introduced by the US Post Office and Royal Mail during the 1970's. The main disadvantages of these types of systems are the necessity to remove items from the OCR flow of items and the ergonomic difficulties experienced by the operator when identifying items transported past the operator.
The next progressive step in the treatment of OCR-rejected items was the item development of an on-line video coding systems (OVS). In an OVS, a video image of the item is presented to the operator for coding in place of the physical items are held in delay loops. In these delay loops, the items are normally held in motion for an interval that is sufficient for the OVS operator to input the necessary sorting information for the respective image. The standard delay loop, the higher the costs as well as the requirements for maintenance and the physical size of the facility.
The main problem when using an OVS is that the available time is only sufficient for a careful input of the zip code (zip) or the postal code (pc), unless delay loops with an impractical length are used.
For this reason, special coding methods were developed to keep the on-line delay time as low as possible.
In order to increase the coding productivity and/ore permit the listing of all address elements, meaning the zip code/postal code, street/post office box, addressee/post office box, addressee/firm, various state-of-the art methods have been developed. Essentially, these include:
Preview Coding
The preview coding involves a simultaneous displays of images from two items, one above the other. In this case, the lower image is the active one, meaning its data is to be encoded first before encoding attention is paid to the upper image. Following a suitable training, an encoding operators can encode information present on the lower image while at the same time recording the address information from the upper image. The upper image subsequently becomes active and the process is continued accordingly. The preview recording permits a doubling of the operator productivity through a complete overlapping of the cognitive and the motorized functions during the coding of successive images.
Extraction Coding
Since only the zip postal code address elements can be input reliably by the operator, given the on-line delay times that are possible in practical operations, specific key components of the address components referring to the street are input during extraction code. The extraction coding normally is based on specially developed rules, for which a code window length is used as an access key to an address directory. For example, the Royal Mail uses an extraction formula that is based in the first three and the last two letters. In that case, the operator must memorize special rules to avoid superfluous address on formation and must take into account specific, differentiating characteristics, e.g. directions such as east, west ore categories such as long as street, lane, road.
Despite a certain effectiveness, the extraction coding has several considerable disadvantages. In particular, it has complex extraction rules, which frequently require taking into account the end of a street name, an address component which is normally written with the least amount of clarity. The extraction coding also involves a significantly high rate of extraction that are not clear and to which several entries in a dictionary correspond. Accordingly, a clear sorting decision cannot always be made. Furthermore, it must be taken into account that the input productivity of the operators is reduced as soon as the operator must make a decisions rather than perform a simpler task such as repetitive keyboard entry.
Completion Coding
In contrast to extraction coding, a variable input is made for the completion coding of each address directory, until both clearly coincide. An acceleration effect is achieved by displaying the remainder of the address as soon as it is recognized from within the directory. However, with this technology problems occur in that an input stop signal must be transmitted to the operator and illustration of the identified remainder of the address is necessary. As a result a reduced input productivity occurs and preview coding is prevented.
Operator-Assisted OCR Technology
The US Postal Service has experimented with operator-assisted OCR techniques to increase the address information to be processed on-line. In this case, the portion of the address image, for which the OCR identification has failed, is emphasized so as to increase effectiveness. Since the operators are slow when deciphering missing letters and since in part complex identification errors, (e.g. segmentation problems) occur as well, the operator productivity with this method is frequently lower than with a simple re-entering of the respective address.
Off-Line Coding
Since a sufficiently high productivity for on-line coding cannot be achieved with any of the above-mentioned coding techniques, an off-line coding system was recently introduced, e.g. as described in the U.S. Pat. No. 4,992,649. As disclosed, items with unidentified addresses are provided with an additional information such as a tracking identification (TID). The unidentified items are stored externally while the images of these items are presented to operators for coding Here, the operator is free from time limits normally associated with on-line coding. The items are subsequently presented to TID readers. The TID is like to the entered address information. Accordingly, a standard bar code sorting information can also be affixed to the item, so that the respective item can be processed in the same was as items that are normally OCR-read. Even though the off-line video coding method is an effective method for cording all address components, the further processing of items with addresses that have not been read requires additional capacities and a correspondingly complex logistic.